[0001] The invention relates generally to reinforced plastic tubulars.
[0002] Filament reinforced tubulars, compared to steel tubulars, are light weight and do
not corrode. Therefore, these type of tubulars are for example highly usable in the
field of geothermal projects.
[0003] In contrast with steel tubulars, filament reinforced tubulars are less suited for
machining, in particular are less suited for providing the tubulars with screw thread
by way of machining.
[0004] It is generally known to machine screw threads, or threading, into the surface of
tubulars. However, with filament reinforced tubulars, the filaments in the tubular
are cut when machining the threading in the tubular. The machining process thus reduces
the strength of the material, and in particular provides screw thread with only a
limited capacity for carrying a load.
[0005] Therefore, with filament reinforced tubulars the screw thread is not cut into the
tubular. To provide a reinforced tubular with the screw thread, the screw thread is
build, with the tubular, on a die. Multiple layers of fiber mats are wound around
a die comprising screw thread. The fiber mats are wound one over the other and are
pushed into the windings of the die. Thus, reinforced screw threads are obtained that
comprise continuous filaments throughout the cross section of the screw thread.
[0006] Unfortunately, the process of building a tubular including the screw thread, can
not be used for tubulars obtained by a centrifugal casting process. In centrifugal
or rotational casting, also known as spin casting or rotational moulding, a thermosetting
resin is forced against an outer mould, which mould has been provided with one or
more fiber mats, the mats comprising filaments in the form of for example glass fibers
with an average length exceeding 50 mm. This process provides high quality tubulars
with superior technical properties.
[0007] It is submitted that it is generally known to use thermoset material, typically in
the form of a thermoset polymer matrix or synthetic matrix, in combination with reinforcements.
In such polymer matrix composites, polymers act as binder or matrix to secure in place
incorporated particulates, fibres or other reinforcements. Continuing research has
led to an increased range of thermoset resins, polymers or plastics for use in the
manufacture of polymer composites.
[0008] It is furthermore submitted that it is generally known to use fibre mats, e.g. glass
fibre mats, as a reinforcement. These mats are layered one on top of the other during
the manufacturing process and are comprised in the matrix material to provide a filament-reinforced
material. Fibre mats may comprise woven or nonwoven glass fibres. Typically, multiple
layers of fibre mats, the mats comprising woven fibre material, are used as a filament
when manufacturing filament-reinforced tubulars.
[0009] As was set out above, machining screw thread into the surface of the tubular would
sever the filaments in the tubular, and therefore reduces the strength of the material.
This is in particular a problem when the tubulars are to be combined into a string
that is suspended in a drilling hole. In such a string the axial load, due to the
weight of the string, on the screw thread would be significant.
[0010] Also, tubulars obtained by centrifugal or rotational casting are made of a thermosetting
material. It is therefore not an option to heat the tubular to temperatures above
melt temperature and subsequently compress the end of the tubular in a mould to obtain
the desired thread configuration in the surface of the tubular.
[0011] Therefore, these type of tubulars are typically connected using glued couplings,
wherein the ends of tubulars are glued one to the other. Compared to screw couplings,
these glued couplings have the drawback that they are time consuming make and are
irreversible. Disconnecting the tubulars requires mechanically removing the coupling,
e.g. by cutting.
[0012] It is an object of the invention to provide an improved filament-reinforced tubular,
preferably of a thermoset material, in which the above mentioned drawbacks are eliminated
altogether or occur in a greatly reduced extent. In particular it is an object of
the first aspect of the invention to provide a centrifugal cast tubular of a thermoset
material with a screw threat.
[0013] According to the present invention, this object is achieved by designing a filament-reinforced
tubular according to claim 1.
[0014] In an embodiment, fibre mats comprising woven glass fibre material are used as a
filament.
[0015] A filament-reinforced tubular, preferably for use in a geothermal well bore, comprises:
a tubular body, the tubular body comprising multiple fibre mats encapsulated in a
thermoset material,
wherein the tubular body is at least at one end, preferably at both ends, provided
with male screw thread, the screw thread comprising threading, with a threading base
and a threading top, and a root groove, with a root base as a bottom, between the
threading,
wherein the threading comprises a core member, the core member having multiple windings
around the tubular body, such that the windings of the core member are separated by
the root base, and wherein the core member extends, at least partially, radially outwards
relative to the root base,
wherein the threading comprises one or more fibre mats that cover the core member,
and wherein the one or more fibre mats are pulled between the windings of the core
member and onto the root base by a positioning wire, and
wherein the core member, the one or more fibre mats, and the positioning wire, are
encapsulated by a thermoset cover material, which cover material defines the shape
of the screw thread.
[0016] The one or more fibre mats that cover the core member, wherein the one or more fibre
mats are pulled between the windings of the core member and onto the root base by
a positioning wire, provide the screw thread with increased strength. In particular,
the fibre mats in combination with the cover material allow for providing the windings
of the screw thread with a core member, thus increasing the structural strength of
the threading, and for a better load transfer from between the screw thread and the
tubular body of the filament-reinforced tubular.
[0017] Preferably, the final form of the screw thread is fully defined by the layer of cover
material, more in particular by the mould used to apply the cover material. In an
embodiment, the cover material bay be subjected to machining to fine tune the dimensional
properties of the screw thread.
[0018] In an embodiment, the core member is created by machining the root groove in the
tubular body, cutting through multiple fibre mats in the tubular body, such that the
core member is formed by part of the tubular body, the part of the core member comprising
multiple fibre mats encapsulated in a thermoset material.
[0019] In this embodiment, the core member is an integral part of the tubular body, and
is a continuation of the material configuration of the tubular body. The layered structure
of the fibre mats in the tubular body continues in the core member. Covering the core
member with multiple fibre mats and a cover material provides a threading with increased
strength and allows for a good load transfer between the threading and the tubular
body.
[0020] In an alternative embodiment, the core member is a strand of filament material, for
example a yarn of reinforcement fibres, the strand of filament material extending
over the tubular body, and thus over the fibre mats in comprised in the tubular body,
and along a length of the threading.
[0021] In this embodiment, the core member is provided as a separated body, which separate
body is integrated in the threading. Providing the core member in the form of a strand
of filament material, extending along the threading, provides the threading with a
continuous structure and thus contributes to the overall strength of the threading.
In particular because the orientation of the threading is parallel to the threading.
[0022] In another alternative embodiment, the core member is a strand of filament material,
for example a yarn of reinforcement fibres, the strand of filament material extending
along a length of the threading, and wherein the threading further comprises:
a core member anchoring area, wherein the anchoring area is created by machining an
anchoring groove in the tubular body, cutting through multiple fibre mats in the tubular
body, such that the windings of the anchoring groove are separated by the root base;
wherein the core member is partially located in the anchoring area, and forms the
core of the threading.
[0023] In this embodiment, the core member is provided as a separated body, that is partially
embedded in the structure of the tubular body. Thus the load transfer between the
threading and the structure of the tubular body section is improved. Providing the
core member in the form of a strand of filament material, extending along the threading,
provides the threading with a continuous structure and thus contributes to the overall
strength of the threading. In particular because the orientation of the threading
is parallel to the threading.
[0024] Thus, in a filament-reinforced tubular according to the invention, the core member
forms the core of the threading. The core member can be an integral part of the tubular
body, comprising multiple fibre mats of the tubular body separated by a root groove
machined in the fibre mats of tubular body, or the core member can be a strand of
filament material, e.g. a strand go glass fibres, wherein the strand of filament material
extends over the tubular body or is partially located in the anchoring groove machined
in the fibre mats of the tubular body. The threading thus comprises the core member,
one or more fibre mats that cover the core member, and a thermoset cover material,
which cover material encapsulates the core member and the fibre mats, and thus defines
the outer shape of the threading.
[0025] It is submitted that providing a filament reinforced tubular with screw thread, in
particular by building a screw thread on the a tubular body, was believed to result
in screw thread having a limited strength. This was in particular the case for tubulars
obtained by centrifugal or rotational casting of a thermoset material.
[0026] It has now been found that providing a tubular body, of a thermoset material and
obtained by centrifugal or rotational casting, with screw thread of which the threading
comprises a core member and fibre mats, which fibre mats are positioned by a positioning
wire and secured in place and a cover layer that also defines the shape of the screw
thread, results in tubulars with improved strength.
[0027] It is submitted that the strength of a tubular, more in particular the strength of
the threading of a tubular, according to the claimed invention allows for constructing
pipe strings, for example for use in a geothermal well bore, wherein the weight load
of the string is transferred via the screw thread of the tubulars, in particular of
tubulars comprising a tubular body obtained by centrifugal or rotational casting of
a thermoset material. Up to now, these kind of strings were build using glued couplings,
which is involves a time consuming and irreversible process. Thus, the invention allows
for tubular strings of filament reinforced tubulars that can be efficiently assembled
and disassembled by using screw couplings.
[0028] In an embodiment of a filament-reinforced tubular according to the invention, the
screw thread is provided on a tapered end section of the tubular, wherein the tapered
end section cuts through multiple fibre mats encapsulated in the thermoset material
of the tubular body. Thus, loads can be transferred via the screw thread to multiple
layers of fibre mats, instead of only to the top layers of fibre mats, of the tubular
body.
[0029] In an embodiment of a filament-reinforced tubular according to the invention, the
tubular body is made by way of centrifugal or rotational casting, preferably by way
of centrifugal or rotational casting a thermosetting material. It is submitted that
the invention is pin particular useful for these kind of tubulars, which up to now
were coupled using glue coupling.
[0030] In an embodiment of a filament-reinforced tubular according to the invention, the
tubular is further provided with a torque-lock mounting area adjacent the screw thread,
wherein the mounting area preferably is provided with grip enhancing surface features
for securing a torque lock against rotation about the longitudinal axis of the tubular,
and wherein the grip enhancing surface features comprise multiple parallel rib elements
and/or parallel slots, for cooperating with rib elements and/or slots provided on
the inside of the torque lock, for securing the torque lock against rotation about
the longitudinal axis of the tubular.
[0031] It is a further object of the invention to provide a riser section comprising two
filament-reinforced tubulars, each provided with screw thread. According to the present
invention, this object is achieved by a riser section according to claim 8.
[0032] Such a riser section comprises two filament-reinforced tubulars according to the
invention and a coupling sleeve connecting the two tubulars, wherein the coupling
sleeve comprises screw thread at opposite ends for cooperating with the screw thread
provided on the tubulars, and wherein the tubulars are each with one end screwed into
the coupling sleeve.
[0033] In an embodiment, the riser section further comprising two torque locks, wherein
the torque locks are mounted each on a tubular, on opposite ends of the coupling sleeve,
wherein the torque locks are on an inside surface provided with grip enhancing surface
features for engaging the grip enhancing surface features of the torque-lock mounting
area of the tubulars, and
wherein the torque locks engage the coupling sleeve such that they block rotation
of the torque
locks relative to the coupling sleeve, to thus secure the respective tubulars against
rotation relative to the coupling sleeve.
[0034] It is a further object of the invention to provide an improved coupling between two
filament-reinforced tubulars, wherein the coupling allows for elongation of the tubulars
when axially loaded. It is yet a further object of the invention to provide a riser
section comprising such an improved coupling. According to the present invention,
this object is achieved by providing a riser section according to claim 10.
[0035] In an embodiment of a riser section according to the invention, the torque locks
engage the coupling sleeve such that they, while blocking rotational movement, allow
for axial movement of the torque locks, and thus of the tubulars, relative to the
coupling sleeve, and thus allow for elongation of the sections of the tubulars comprising
the screw thread, when the tubulars are loaded in an axial direction.
[0036] In a further embodiment of a riser section according to the invention, the torque
locks are provided with coupling teeth, the coupling teeth extending in an axial direction,
and wherein the coupling sleeve is at opposite ends provided with coupling teeth,
the coupling teeth extending in an axial direction, and wherein the coupling teeth
of the torque locks are configured to cooperate with the coupling teeth of the coupling
sleeve, and wherein the coupling teeth of the coupling sleeve are configured to cooperate
with the coupling teeth of the torque locks.
[0037] In an embodiment of a riser section according to the invention, the coupling sleeve
is made of steel, and wherein preferably the torque locks are made of steel.
[0038] In an embodiment of a riser section according to the invention, the screw thread
of the coupling sleeve and the screw thread of the respective tubulars is configured
to compensate for elongation of the tubulars, in particular of the section of the
tubulars provided with screw thread, and preferably, wherein the screw thread on the
tubulars, and the corresponding screw thread on the coupling sleeve, is provided on
tapered section of the tubular and a tapered section of the coupling sleeve respectively.
[0039] In an embodiment of a riser section according to the invention, the pitch of the
screw thread, i.e. the distance between adjacent windings, of the tubulars increases
in a direction away from the end of the tubular, and the pitch of the screw threads
of the coupling sleeve increases in a direction towards the end of the coupling sleeve,
such that, when the tubulars are screwed into the coupling sleeve and the torque locks
have been mounted to secure the rotational movement of the tubulars relative to the
coupling sleeve:
- in an unloaded condition, i.e. when there is no or only a limited axial load on the
tubulars, only a limited number of windings, i.e. for the tubular windings located
near the end of the tubular and for the coupling sleeve windings located away of the
end of the coupling sleeve, is in engagement;
- during an increase in axial load on the riser section, the tubulars, and in particular
the section of the tubular comprising the screw thread, elongates, and an increasing
number of windings of the tubulars come into engagement with the windings of the coupling
sleeve; and
- in a fully loaded condition, i.e. when there is a significant axial load on the tubulars
e.g. by the riser section supporting a riser hanging in a bore hole, all windings,
i.e. for the tubular also the windings located away from the end of the tubular and
for the coupling sleeve also the windings located near the end of the coupling sleeve,
are in engagement.
[0040] In an embodiment of a riser section according to the invention, the coupling sleeve
is provided with one or two sealing rings, such that the tubulars, when screwed into
the couplings sleeve, abut a sealing ring with an outer end thereof.
[0041] The invention furthermore provides a tubular for providing a riser section according
to the invention.
[0042] The invention furthermore provides a coupling assembly, comprising a coupling sleeve
and two torque locks, for providing a riser section according to the invention.
[0043] The invention furthermore provides a riser comprising multiple riser sections according
to the invention.
[0044] The invention furthermore provides a bore hole, preferably geothermal bore hole,
provided with a string of tubulars comprising tubulars according to the invention,
preferably comprising riser sections according to the invention.
[0045] The invention furthermore provides a geothermal facility comprising a bore hole according
to the invention.
[0046] It is a further object of the invention to provide a method for obtaining a filament-reinforced
tubular provided with screw thread. According to the present invention, this object
is achieved by providing a method according to claim 21.
[0047] A method for providing a filament reinforced tubular with screw thread, preferably
to provide a tubular according to the invention,
wherein the screw thread comprises threading, the threading having a threading base
and a threading top, and a root groove between the threading, the root groove having
a root base as a bottom, and
wherein the filament reinforced tubular comprising a tubular body, and the tubular
body comprising multiple fibre mats encapsulated in a thermoset material,
comprises:
- optionally: machining a tapered end on the tubular body, such that multiple layers
of fibre mats of the tubular body are exposed;
- providing the tubular with a core member for the threading, preferably at the tapered
end of the tubular body, the core member having multiple windings around the tubular
body, such that the windings of the core member are separated by the root base, and
wherein the core member extends, at least partially, radially outwards relative to
the root base;
- winding one or more fibre mats around the core member and the root groove, preferably
such that fibres in the fibre mat run parallel to the root groove cut in the tubular;
- winding a positioning wire into the root groove, thus pulling the one or more fibre
mats between the windings of the core member and onto the root base, preferably, the
positioning wire is received in a fibre math, and the previous two steps are combined;
- inserting fibre mat covered end of the tubular into a mould, wherein the mould defines
the final shape of the screw thread;
- injecting a cover material, preferably a thermoset cover material e.g. a molten resin,
under pressure into a cavity between the end of the tubular and the mould, thus encapsulating
the core member, the one or more fibre mats, and the positioning wire, and thus defining
the shape of the screw thread;
- after a setting period, increase pressure in the thermoset cover material to remove
air bubbles from the mould; and
- removing the tubular from the mould.
[0048] In an embodiment, the method further comprises:
creating the core member for the threading by machining the root groove in the tubular
body, preferably in the tapered end of the tubular body, thus cutting through multiple
fibre mats in the tubular body, such that the core member for the threading is formed
by part of the tubular body, the part of the core member comprising multiple fibre
mats encapsulated in a thermoset material.
[0049] In an alternative embodiment, the method further comprises:
providing the core member as a strand of filament material, for example a yarn of
reinforcement fibres, winding the strand of filament material around the tubular body
such that the strand of filament material extends over the tubular body, and thus
over the fibre mats in comprised in the tubular body, and along a length of the threading
to be provided.
[0050] In an alternative embodiment, the method further comprises:
creating a core member anchor area by machining an anchoring groove in the tubular
body, cutting through multiple fibre mats in the tubular body, such that the windings
of the anchoring groove are separated by the root base; and
providing the core member as a strand of filament material, for example a yarn of
reinforcement fibres, winding the strand of filament material in the anchoring groove
around the tubular body such that the strand of filament material extends along a
length of the threading to be provided, and such that the core member is partially
located in the anchor area, to form the core of the threading.
[0051] In an embodiment of the method, the positioning wire is received, preferably is integrated,
in a strip shaped fibre mat, preferably along a side of the strip shaped fibre mat,
and wherein the strip shaped fibre mat, more in particular the positioning wire, is
wound around the tapered part of the tubular such that the subsequent windings of
the strip shaped fibre mat overlap each other.
[0052] In an embodiment of the method, the tubular body of the filament reinforced tubular
is obtained by rotational casting.
[0053] In an embodiment, the positioning wire comprises the same material as the reinforcing
material of the tubular, for example comprises glass fibres woven into a strand. In
an embodiment, the positioning wire is a strand of filament material, for example
a yarn of reinforcement fibres.
[0054] Advantageous embodiments of the Filament reinforced tubular according to the invention
and the method according to the invention are disclosed in the sub claims and in the
description, in which the invention is further illustrated and elucidated on the basis
of a number of exemplary embodiments, of which some are shown in the schematic drawing.
In the figures, components corresponding in terms or construction and/or function
are provided with the same last two digits of the reference numbers.
[0055] Whilst primarily presented for illustrative purposes with reference to one or more
of the figures, any of the technical features addressed below may be combined with
any of the independent claims of this application either alone or in any other technically
possible combination with one or more other technical features.
[0056] In the drawings:
Fig. 1 schematically shows a side view of an exemplary embodiment of a filament-reinforced
tubular according to the in the invention;
Fig. 2 schematically shows an enlarged partial side view in cross section of threading
of the exemplary embodiment of a filament-reinforced tubular of fig. 1;
Fig. 3 schematically shows an enlarged partial side view in cross section of threading
of an alternative exemplary embodiment of a filament-reinforced tubular;
Fig. 4 schematically shows an enlarged partial side view in cross section of threading
of another alternative exemplary embodiment of a filament-reinforced tubular;
Fig. 5 schematically shows a side view of an exemplary embodiment of a riser section
comprising two filament-reinforced tubulars coupled via a coupling sleeve according
to the in the invention; and
Fig. 6 schematically shows an enlarged partial exploded view in cross section of the
exemplary riser section of fig. 5.
Figure 1 shows a side view of a filament-reinforced tubular 1 according to the claimed
invention. The filament reinforced tubular 1 comprises a tubular body 2.
[0057] It is submitted that such a filament-reinforced tubular is in particular suitable
for use in a geothermal well bore, i.e. for contrasting a riser to be suspended in
a well bore of a geothermal facility.
[0058] According to the invention, the filament-reinforced tubular 1 is provided with screw
thread 3, more in particular a tubular body is provided with screw thread. In the
embodiment shown, the tubular body 2 is at both ends, on tapered end sections of the
tubular body, provided with male screw thread 3. The screw thread is built on the
tubular body, as will be explained below.
[0059] Figure 2 schematically shows an enlarged partial side view in cross section of threading,
and part of the tubular body 2, of the screw thread of the filament-reinforced tubular
of fig. 1;
[0060] The screw thread 3 comprises threading 5. The threading has a threading base 6, a
threading top 7, and a root groove 8, with a root base 9 as a bottom, located between
the threading 5.
[0061] The tubular body 2 comprising multiple fibre mats 10 encapsulated in a thermoset
material 11.
[0062] According to the invention, the threading 5 comprises a core member 12. The core
member 12 has multiple windings around the tubular body 2, such that the windings
of the core member are separated by the root base 9. The core member 12 forms the
core of the threading, and extends radially outwards relative to the root base 9.
[0063] The threading 5 comprises one or more fibre mats 13, in the embodiment shown multiple
fibre mats depicted as a single layer of fibre mats, that cover the core member 12.
The fibre mats 13 are pulled between the windings of the core member 12 and onto the
root base 9 by a positioning wire 14.
[0064] The core member 12, the one or more fibre mats 13, and the positioning wire 14, are
encapsulated by a thermoset cover material 15, which cover material defines the shape
of the screw thread 3.
[0065] In the exemplary embodiment shown in figure 1 and figure 2, the core member 12 is
created by machining the root groove 8 in the tubular body 2, cutting through multiple
fibre mats 10 in the tubular body 2, such that the core member 12 is formed by a part
of the tubular body.
[0066] The core member 12 comprises multiple fibre mats 13 encapsulated in a thermoset material.
[0067] In this embodiment, the core member 12 is an integral part of the original tubular
body 2, and is a continuation of the material configuration of that tubular body.
More in particular, the layered structure of the fibre mats 10 in the tubular body
continues 2 in the core member 12. Covering the core member with multiple fibre mats
13 and the cover material 15 provides a threading with increased strength and allows
for a good load transfer between the threading and the tubular body.
[0068] In an alternative embodiment, shown in figure 3, the core member 12 is a strand of
filament material 16, for example a yarn of reinforcement fibres. The strand of filament
material 16, depicted in cross section perpendicular to the length of the strand,
extends over the tubular body 2, and thus over the fibre mats 10 in comprised in the
tubular body, and along a length of the threading.
[0069] In this embodiment, the core member 12 is provided as a separated body, i.e. strand
16, which separate body is integrated in the threading. Providing the core member
12 in the form of a strand of filament material, extending along the threading, provides
the threading with a continuous structure and thus contributes to the overall strength
of the threading. In particular because the orientation of the threading is parallel
to the threading.
[0070] In another alternative embodiment, shown in figure 4, the core member 12 is a strand
of filament material 15, extending along a length of the threading, received in a
core member anchoring area 17 of the tubular body 2.
[0071] The anchoring area 17 is created by machining an anchoring groove in the tubular
body 2, cutting through multiple fibre mats 10 in the tubular body, such that the
windings of the anchoring groove are separated by the root base 9. The core member
12 is partially located in the anchor area 17, extends in the radial direction relative
to the tubular body and thus also extends partially in the threading. The core member
is thus anchored in the tubular body and forms the core of the threading.
[0072] In this embodiment, the core member 12 is, similar to the embodiment shown in figure
3, provided as a separated body. In contrast with that embodiment, the core member
is partially embedded in the structure of the tubular body. Thus the load transfer
between the threading and the structure of the tubular body section is improved. Providing
the core member in the form of a strand of filament material, extending along the
threading, provides the threading with a continuous structure and thus contributes
to the overall strength of the threading. In particular because the orientation of
the threading is parallel to the threading.
[0073] Figure 5 schematically shows a side view of an exemplary embodiment of a riser section
18 comprising two filament-reinforced tubulars 1, coupled via a coupling sleeve 19,
according to the in the invention.
[0074] Figure 6 schematically shows an enlarged partial exploded view in cross section of
the exemplary riser section 18, depicting part of the tubulars 1, part of the coupling
sleeve 19 connecting the two tubulars, part of two torque locks 20 mounted on the
tubulars, and part of a sealing ring 21, located between the ends of the two tubulars.
[0075] The two filament-reinforced tubulars 1 are each, at tapered end sections 4, provided
with screw thread 3. The coupling sleeve 19 comprises screw thread 22 at opposite
ends for cooperating with the screw thread 3 provided on the tubulars 1. The tubulars
are each with one end screwed into the coupling sleeve.
[0076] In the embodiment shown, the riser section 18 further comprising two torque locks
20. The torque locks 20 are each mounted on a tubular 1, on opposite ends of the coupling
sleeve 19. The torque locks 20 are on an inside surface provided with grip enhancing
surface features 23 for engaging grip enhancing surface features 24 of a torque-lock
mounting area of the tubulars.
[0077] The torque locks 20 engage the coupling sleeve 19 such that they block rotation of
the torque locks relative to the coupling sleeve 19, to thus secure the respective
tubulars against rotation relative to the coupling sleeve.
[0078] In the embodiment shown, the torque locks 20 engage the coupling sleeve 19 such that
they, while blocking rotational movement, allow for axial movement of the torque locks
20, and thus of the tubulars 1, relative to the coupling sleeve 19,. The torque locks
and the coupling sleeve thus allow for elongation of the sections of the tubulars
comprising the screw thread, when the tubulars are loaded in an axial direction.
[0079] It is noted that due to the section of the tubulars being tapered, to connected the
threading with multiple layers of fibre mats in the tubular body, under load the tapered
section may not show a linear elongation profile. Preferably, the screw thread of
the coupling sleeve and the tubulars is configured to establish a uniform load transfer
between the tubulars and the coupling sleeve. Preferably, the pitch of the screw thread,
i.e. the distance between adjacent windings, of the tubulars increases in a direction
away from the end of the tubular, and the pitch of the screw threads of the coupling
sleeve increases in a direction towards the end of the coupling sleeve, such that,
when the tubulars are screwed into the coupling sleeve and the torque locks have been
mounted to secure the rotational movement of the tubulars relative to the coupling
sleeve:
- in an unloaded condition, i.e. when there is no or only a limited axial load on the
tubulars, only a limited number of windings, i.e. for the tubular windings located
near the end of the tubular and for the coupling sleeve windings located away of the
end of the coupling sleeve, is in engagement;
- during an increase in axial load on the riser section, the tubulars, and in particular
the section of the tubular comprising the screw thread, elongate, and an increasing
number of windings of the tubulars come into engagement with the windings of the coupling
sleeve; and
- in a fully loaded condition, i.e. when there is a significant axial load on the tubulars
e.g. by the riser section supporting a riser handing in a bore hole, all windings,
i.e. for the tubular also the windings located away from the end of the tubular and
for the coupling sleeve also the windings located near the end of the coupling sleeve,
are in engagement.
[0080] The invention can be summarized according to one or more of the following clauses:
- 1. Filament-reinforced tubular, preferably for use in a geothermal well bore, wherein
the filament reinforced tubular comprises:
a tubular body, the tubular body comprising multiple fibre mats encapsulated in a
thermoset material,
wherein the tubular body is at least at one end, preferably at both ends, provided
with male screw thread, the screw thread comprising threading, with a threading base
and a threading top, and a root groove, with a root base as a bottom, between the
threading,
wherein the threading comprises a core member, the core member having multiple windings
around the tubular body, such that the windings of the core member are separated by
the root base, and wherein the core member extends, at least partially, radially outwards
relative to the root base,
wherein the threading comprises one or more fibre mats that cover the core member,
and wherein the one or more fibre mats are pulled between the windings of the core
member and onto the root base by a positioning wire, and
wherein the core member, the one or more fibre mats, and the positioning wire, are
encapsulated by a, preferably thermoset, cover material, which cover material defines
the shape of the screw thread.
- 2. Filament-reinforced tubular according to clause 1, wherein the core member is created
by machining the root groove in the tubular body, cutting through multiple fibre mats
in the tubular body, such that the core member is formed by a part of the tubular
body, the part of the core member comprising multiple fibre mats encapsulated in a
thermoset material.
- 3. Filament-reinforced tubular according to clause 1, wherein the core member is a
strand of filament material, for example a yarn of reinforcement fibres, e.g. glass
fibres, the strand of filament material extending over the tubular body, and thus
over the fibre mats comprised in the tubular body, and along a length of the threading.
- 4. Filament-reinforced tubular according to clause 1, wherein the core member is a
strand of filament material, for example a yarn of reinforcement fibres, the strand
of filament material extending along a length of the threading, and wherein the threading
further comprises:
- a core member anchoring area, wherein the anchoring area is created by machining an
anchoring groove in the tubular body, cutting through multiple fibre mats in the tubular
body, such that the windings of the anchoring groove are separated by the root base;
wherein the core member is partially located in the anchoring area, and forms the
core of the threading.
- 5. Filament-reinforced tubular according to one or more of the preceding clauses,
wherein the screw thread is provided on a tapered end section of the tubular, wherein
the tapered end section cuts through multiple fibre mats encapsulated in the thermoset
material of the tubular body.
- 6. Filament-reinforced tubular according to one or more of the preceding clams, wherein
the tubular body is made by way of centrifugal or rotational casting, preferably by
way of centrifugal or rotational casting a thermosetting material.
- 7. Filament-reinforced tubular according to one or more of the preceding clams, wherein
the tubular is further provided with a torque-lock mounting area adjacent the screw
thread, wherein the mounting area preferably is provided with grip enhancing surface
features for securing a torque lock against rotation about the longitudinal axis of
the tubular, and wherein the grip enhancing surface features comprise multiple parallel
rib elements and/or parallel slots, for cooperating with rib elements and/or slots
provided on the inside of the torque lock, for securing the torque lock against rotation
about the longitudinal axis of the tubular.
- 8. Riser section comprising two filament-reinforced tubulars according to one or more
of the preceding clauses and a coupling sleeve connecting the two tubulars, wherein
the coupling sleeve comprises screw thread at opposite ends for cooperating with the
screw thread provided on the tubulars, and wherein the tubulars are each with one
end screwed into the coupling sleeve.
- 9. Riser section according to clause 7 and clause 8, the riser section further comprising
two torque locks, wherein the torque locks are mounted each on a tubular, on opposite
ends of the coupling sleeve,
wherein the torque locks are on an inside surface provided with grip enhancing surface
features for engaging the grip enhancing surface features of the torque-lock mounting
area of the tubulars, and
wherein the torque locks engage the coupling sleeve such that they block rotation
of the torque locks relative to the coupling sleeve, to thus secure the respective
tubulars against rotation relative to the coupling sleeve.
- 10. Riser section according to clause 9, wherein the torque locks engage the coupling
sleeve such that they, while blocking rotational movement, allow for axial movement
of the torque locks, and thus of the tubulars, relative to the coupling sleeve, and
thus allow for elongation of the sections of the tubulars comprising the screw thread,
when the tubulars are loaded in an axial direction.
- 11. Riser section according to clause 9 or clause 10, wherein the torque locks are
provided with coupling teeth, the coupling teeth extending in an axial direction,
and
wherein the coupling sleeve is at opposite ends provided with coupling teeth, the
coupling teeth extending in an axial direction, and wherein the coupling teeth of
the torque locks are configured to cooperate with the coupling teeth of the coupling
sleeve, and wherein the coupling teeth of the coupling sleeve are configured to cooperate
with the coupling teeth of the torque locks.
- 12. Riser section according to one or more of the clauses 8-11, wherein the coupling
sleeve is made of steel, and wherein preferably the torque locks are made of steel.
- 13. Riser section according to one or more of the clauses 8-12, wherein the screw
thread of the coupling sleeve and the screw thread of the respective tubulars is configured
to compensate for elongation of the tubulars, in particular of the section of the
tubulars provided with screw thread, and preferably, wherein the screw thread on the
tubulars, and the corresponding screw thread on the coupling sleeve, is provided on
tapered section of the tubular and a tapered section of the coupling sleeve respectively.
- 14. Riser section according to clause 13, wherein the pitch of the screw thread, i.e.
the distance between adjacent windings, of the tubulars increases in a direction away
from the end of the tubular, and the pitch of the screw threads of the coupling sleeve
increases in a direction towards the end of the coupling sleeve, such that, when the
tubulars are screwed into the coupling sleeve and the torque locks have been mounted
to secure the rotational movement of the tubulars relative to the coupling sleeve:
- in an unloaded condition, i.e. when there is no or only a limited axial load on the
tubulars, only a limited number of windings, i.e. for the tubular windings located
near the end of the tubular and for the coupling sleeve windings located away of the
end of the coupling sleeve, is in engagement;
- during an increase in axial load on the riser section, the tubulars, and in particular
the section of the tubular comprising the screw thread, elongates, and an increasing
number of windings of the tubulars come into engagement with the windings of the coupling
sleeve; and
- in a fully loaded condition, i.e. when there is a significant axial load on the tubulars
e.g. by the riser section supporting a riser hanging in a bore hole, all windings,
i.e. for the tubular also the windings located away from the end of the tubular and
for the coupling sleeve also the windings located near the end of the coupling sleeve,
are in engagement.
- 15. Riser section according to one or more of the clauses 8-14, wherein the coupling
sleeve is provided with one or two sealing rings, such that the tubulars, when screwed
into the couplings sleeve, abut a sealing ring with an outer end thereof.
- 16. Tubular for providing a riser section according to clause 14 or clause 15.
- 17. Coupling assembly, comprising a coupling sleeve and two torque locks, for providing
a riser section according to one or more of the clauses 8-15.
- 18. Riser comprising multiple riser sections according to one or more of the clauses
8-15.
- 19. Bore hole, preferably a geothermal bore hole, provided with a string of tubulars
comprising tubulars according to one or more of the clauses 1-7, preferably comprising
riser sections according to one or more of the clauses 8-15.
- 20. Geothermal facility comprising a bore hole according to clause 19.
- 21. Method for providing a filament reinforced tubular with screw thread, preferably
to provide a tubular according to one or more of the clauses 1-7,
wherein the screw thread comprises threading, the threading having a threading base
and a threading top, and a root groove between the threading, the root groove having
a root base as a bottom, and
wherein the filament reinforced tubular comprising a tubular body, and the tubular
body comprising multiple fibre mats encapsulated in a thermoset material, the method
comprising:
- optionally: machining a tapered end on the tubular body, such that multiple layers
of fibre mats of the tubular body are exposed;
- providing the tubular with a core member for the threading, preferably at the tapered
end of the tubular body, the core member having multiple windings around the tubular
body, such that the windings of the core member are separated by the root base, and
wherein the core member extends, at least partially, radially outwards relative to
the root base;
- winding one or more fibre mats around the core member and the root groove, preferably
such that fibres in the fibre mat run parallel to the root groove in the tubular;
- winding a positioning wire into the root groove, thus pulling the one or more fibre
mats between the windings of the core member and onto the root base;
- inserting fibre mat covered end of the tubular into a mould, wherein the mould defines
the final shape of the screw thread;
- injecting a cover material, preferably a thermoset cover material e.g. a molten resin,
under pressure into a cavity between the end of the tubular and the mould, thus encapsulating
the core member, the one or more fibre mats, and the positioning wire, and thus defining
the shape of the screw thread;
- after a setting period, increase pressure in the thermoset cover material to remove
air bubbles from the mould; and
- removing the tubular from the mould.
- 22. Method according to clause 21, wherein the method further comprises:
creating the core member for the threading by machining the root groove in the tubular
body, preferably in the tapered end of the tubular body, thus cutting through multiple
fibre mats in the tubular body, such that the core member for the threading is formed
by part of the tubular body, the part of the core member comprising multiple fibre
mats encapsulated in a thermoset material.
- 23. Method according to clause 21, wherein the method further comprises:
providing the core member as a strand of filament material, for example a yarn of
reinforcement fibres, winding the strand of filament material around the tubular body
such that the strand of filament material extends over the tubular body, and thus
over the fibre mats in comprised in the tubular body, and along a length of the threading
to be provided.
- 24. Method according to clause 21, wherein the method further comprises:
creating a core member anchor area by machining an anchoring groove in the tubular
body, cutting through multiple fibre mats in the tubular body, such that the windings
of the anchoring groove are separated by the root base; and
providing the core member as a strand of filament material, for example a yarn of
reinforcement fibres, winding the strand of filament material in the anchoring groove
around the tubular body such that the strand of filament material extends along a
length of the threading to be provided, and such that the core member is partially
located in the anchor area, to form the core of the threading.
- 25. Method according to one or more of the clauses 21-24, wherein the positioning
wire is received, preferably is integrated, in a strip shaped fibre mat, preferably
along a side of the strip shaped fibre mat, and wherein the strip shaped fibre mat,
more in particular the positioning wire, is wound around the tapered part of the tubular
such that the subsequent windings of the strip shaped fibre mat overlap each other.
- 26. Method according to one or more of the clauses 21-25, wherein the tubular body
of the filament reinforced tubular is obtained by rotational casting.
Reference signs
[0081]
01 filament-reinforced tubular
02 tubular body
03 screw thread
04 tapered end sections of the tubular body
05 threading
06 threading base
07 threading top
08 root groove
09 root base
10 fibre mats in tubular body
11 thermoset material
12 core member
13 fibre mats that cover the core member
14 positioning wire
15 thermoset cover material
16 strand of filament material
17 core member anchoring area
18 riser section
19 coupling sleeve
20 torque locks
21 sealing ring
22 screw thread coupling sleeve
23 grip enhancing surface features torque lock
24 grip enhancing surface features torque lock mounting area tubular
1. Riser section comprising two filament-reinforced tubulars and a coupling sleeve connecting
the two tubulars, wherein the coupling sleeve comprises screw thread at opposite ends
for cooperating with the screw thread provided on the tubulars, and wherein the tubulars
are each with one end screwed into the coupling sleeve,
wherein the riser section further comprising two torque locks, wherein the torque
locks are mounted each on a tubular, on opposite ends of the coupling sleeve, wherein
the torque locks are on an inside surface provided with grip enhancing surface features
for engaging grip enhancing surface features of a torque-lock mounting area of the
tubulars, and
wherein the torque locks engage the coupling sleeve such that they block rotation
of the torque locks relative to the coupling sleeve, to thus secure the respective
tubulars against rotation relative to the coupling sleeve,
wherein the torque locks engage the coupling sleeve such that they, while blocking
rotational movement, allow for axial movement of the torque locks, and thus of the
tubulars, relative to the coupling sleeve, and thus allow for elongation of the sections
of the tubulars comprising the screw thread, when the tubulars are loaded in an axial
direction; and
wherein the pitch of the screw thread, i.e. the distance between adjacent windings,
of the tubulars increases in a direction away from the end of the tubular, and the
pitch of the screw threads of the coupling sleeve increases in a direction towards
the end of the coupling sleeve, such that, when the tubulars are screwed into the
coupling sleeve and the torque locks have been mounted to secure the rotational movement
of the tubulars relative to the coupling sleeve:
- in an unloaded condition, i.e. when there is no or only a limited axial load on
the tubulars, only a limited number of windings, i.e. for the tubular windings located
near the end of the tubular and for the coupling sleeve windings located away of the
end of the coupling sleeve, is in engagement;
- during an increase in axial load on the riser section, the tubulars, and in particular
the section of the tubular comprising the screw thread, elongates, and an increasing
number of windings of the tubulars come into engagement with the windings of the coupling
sleeve; and
- in a fully loaded condition, i.e. when there is a significant axial load on the
tubulars e.g. by the riser section supporting a riser hanging in a bore hole, all
windings, i.e. for the tubular also the windings located away from the end of the
tubular and for the coupling sleeve also the windings located near the end of the
coupling sleeve, are in engagement.
2. Riser section according to claim 1, wherein a tubular body of each of the tubulars
is made by way of centrifugal or rotational casting, preferably by way of centrifugal
or rotational casting a thermosetting material.
3. Riser section according to claim 1 or claim 2, wherein each of the tubulars is further
provided with the torque-lock mounting area adjacent the screw thread, wherein the
mounting area is provided with grip enhancing surface features for securing a torque
lock against rotation about the longitudinal axis of the tubular, and wherein the
grip enhancing surface features comprise multiple parallel rib elements and/or parallel
slots, for cooperating with rib elements and/or slots provided on the inside of the
torque lock, for securing the torque lock against rotation about the longitudinal
axis of the tubular.
4. Riser section according to any of the preceding claims, wherein the torque locks are
provided with coupling teeth, the coupling teeth extending in an axial direction,
and wherein the coupling sleeve is at opposite ends provided with coupling teeth,
the coupling teeth extending in an axial direction, and wherein the coupling teeth
of the torque locks are configured to cooperate with the coupling teeth of the coupling
sleeve, and wherein the coupling teeth of the coupling sleeve are configured to cooperate
with the coupling teeth of the torque locks.
5. Riser section according to any of the preceding claims, wherein the coupling sleeve
is made of steel, and wherein preferably the torque locks are made of steel.
6. Riser section according to any of the preceding claims, wherein the coupling sleeve
is provided with one or two sealing rings, such that the tubulars, when screwed into
the couplings sleeve, abut a sealing ring with an outer end thereof.
7. Tubular for providing a riser section according to any of the preceding claims.
8. Coupling assembly, comprising a coupling sleeve and two torque locks, for providing
a riser section according to any of the preceding claims.
9. Riser comprising multiple riser sections according to any of the claims 1-6.
10. Bore hole, preferably a geothermal bore hole, provided with a string of tubulars comprising
riser sections according to any of the claims 1-6.
11. Geothermal facility comprising a bore hole according to claim 10.